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Electric Vehicle Charging 101

As any enthusiast, or anyone tracking the automotive industry, can see, electric vehicles (EVs) are inevitably going to be a way of life in the near future. The best evidence of this, besides almost every major manufacturer developing an electric car, is the new Corporate Average Fuel Economy (CAFE) standard put into place by the Obama Administration. By 2025 every new vehicle sold in the United States will need to get at least 54.5 mpg. Plug-in hybrid EVs and EVs operate on batteries that need to be charged periodically. Because of the inevitability of the EV, it is important to understand how to charge or “fuel” them.

When Ford’s Model T came out in 1908, there were no gas stations. People had to go to kerosene factories for their fuel. The Model T, however, was so affordable that a surge in the number of automobile owners occurred and the demand for gasoline rose. So gas stations were born to meet the growing needs of automobile owners. With these new CAFE standards history is poised to repeat itself only this time with EVs. The demand is rising and networks of charging stations are popping up to meet that demand.

Ford Model T

Different EVs have different specifications and different chargers have different capabilities. Understanding these various capabilities can be difficult. Electricity is invisible and has a fairly complicated array of measurements to gauge the speed and the amount being used and transferred to an EV. Wattage, amperage, voltage, the type of current (direct or alternating) and phases all come into play. Other factors to consider are the various plugs for different countries and within those countries or, conversely, whether a charger is hardwired. A slightly less important aspect is the plug that goes into the vehicle. It is slightly less significant because this has been standardized (SAE J1772) for North America and later this year a global standard will be chosen.

SAE J1772 Electric Vehicle Plug

The most important figures people need to know when determining how best to charge their vehicle are kilowatts (kW) and kilowatts per hour (kWh). kWh is a measurement of a battery’s capacity to store energy and kW is a measurement of a charger’s capacity to deliver electricity to a vehicle. The time in hours it will take to charge an EV can be determined by dividing the kWh of the battery by the kW of the charger. The equation to determine a charger’s kW takes into account volts, amperes, whether the charger is using a direct current and in the case of alternating currents, the power factor, single-phase or three-phase are also part of the equation. Understanding all this electrical terminology is a great idea for EV owners but the simplest way to consider charging is through kilowatts (see chart below).

The levels of charging (one, two and three) are a good way of generalizing types of charging but within some of the levels there can be a lot of variation. Within level one, for example, the kW can range from 1.6 to almost 4 with a higher voltage. Within level two, the kW can range from about 7 to almost 44. Level three is a little simpler and much more powerful. Today, level three chargers are expensive but they can also charge an EV with incredible speed, sometimes in 15 minutes. Level three chargers use a direct current, extremely high voltage and amperage. They range from 40kW to 50kW.

Understanding the kW of varying chargers is good, but it’s only half of the equation. The capability of the car is the other half. There are several commercialized EVs that don’t have the ability to take full advantage of level two or level three charging. A car with a 16 kWh battery, for example, may only be able to accept 16 amps so some level two chargers with high amperage (32A – 63A) and a somewhat low voltage (240V) would charge the vehicle at the same speed as a level one with low amperage (16A) and similar voltage (240V).

The best advice for anyone purchasing an EV or an EV charger is to do your research or make sure the company you are buying from is doing their research and is well informed. EVs are here to stay and understanding how best to “fuel” your vehicle is critical for consumers. With rapidly progressing battery and charging technology it can be a little confusing to keep, but like any new technology the kinks will all get worked out.

The future of vehicle charging is bright. Beyond the three levels of charging there is a new technology that has very recently been commercialized and because of its convenience and speed it will undoubtedly be the way to charge in the future. Inductive (or wireless) charging has the same, if not better speed capabilities as level three charging. Wireless charging will soon become a reality for at least two major EV models in the US. The new chargers will be 240V and charge vehicles, on average, in about half the time it would take for a level one charger.

Electric Bus Charging Wirelessly – South Korea

In the not too distant future we can expect to see wireless charging built into the roads. Some EV manufacturers have been looking into wireless charging as part of roadside infrastructure for 18-wheelers and buses. A company in Korea already has a small network of wireless charging roads for buses as part of their public transportation. As these wireless-charging technologies become cheaper to produce we will leave gas stations and pollution behind for a cleaner electrified future!